Enter age, height and weight, select pregnancy or postpartum, and add optional risk factors. The calculator totals VTE (venous thromboembolism) risk points and shows a simple risk band. Use with a clinician.
* The percentage is illustrative, not a measured personal chance. Use the guideline score with your clinician; pregnancy and postpartum treatment thresholds differ.
How to use this calculator
- Select units, then enter height and weight, or leave blank to use a typical BMI of 26.
- Enter age, or tick older than 35 to apply that item.
- Select pregnancy or postpartum.
- Open Advanced to add optional risk factors. Each item shows its points.
- Press Calculate. The output shows the total score, the BMI used, and a simple risk band.
For counselling only. Use with clinical judgement and local guidance.
Calculator updated: September 13, 2026
Methodology and sources
The points follow RCOG 37a’s September 2026 amended assessment. Surgery, hospital/IV-treated systemic infection, and immobility or dehydration each add 4 points; BMI 50 or more adds 4. ART/IVF counts only during pregnancy; completed-birth items count only postpartum. Alternative birth methods and previous-VTE categories are not added together. The percentage is an illustrative score-based estimate, not a validated personal probability or an RCOG percentage. Score bands alone do not decide treatment; prior VTE, thrombophilia, hospital admission, bleeding risk and temporary illness require clinical assessment.
What this tool calculates
- A point based pregnancy and postpartum venous thromboembolism (VTE) risk score styled on RCOG 37a risk assessment.
- A simple banded interpretation: 0 to 1 low, 2 to 3 moderate, 4 or more higher.
Inputs and point scheme
- Age older than 35: 1 point.
- Body mass index: 1 point if BMI 30 or more, 2 points at BMI 40–49, and 4 points at BMI 50 or more.
- Pre existing factors: previous VTE, thrombophilia, selected medical comorbidities, family history, parity 3 or more, smoking, gross varicose veins. Points match the values shown in the calculator.
- Obstetric factors: pre eclampsia, assisted reproduction, multiple pregnancy, mode of birth, prolonged labour, postpartum haemorrhage, preterm birth, stillbirth. Points match the values shown in the calculator.
- Transient factors: surgery in pregnancy or puerperium, hyperemesis, ovarian hyperstimulation syndrome, systemic infection, immobility or dehydration. Points match the values shown in the calculator.
Computation
- Total score equals the sum of selected item points.
- Bands provide a plain language summary to support counselling. Decisions follow local protocol.
BMI handling
- If height and weight are entered, BMI is calculated from the chosen units.
- If left blank, BMI defaults to 26 so obesity points are not applied.
Scope and limits
- Use in pregnancy and up to 6 weeks postpartum for singleton or multiple pregnancies.
- Risk assessment should be repeated with changes in status, admission, or at birth, in line with guideline practice.
- This tool does not initiate, adjust, or withhold treatment. Use shared decision making and local pathways.
Sources
- RCOG Green top Guideline 37a, Reducing the risk of thrombosis and embolism during pregnancy and the puerperium. Guideline page and PDF: rcog.org.uk guideline page, rcog.org.uk PDF.
- NICE resource, RCOG obstetric thromboprophylaxis risk assessment tool (score sheet). nice.org.uk risk tool PDF.
- ACOG Practice Bulletin, Thromboembolism in Pregnancy, overview page. acog.org practice bulletin.
- Queensland Health Clinical Guideline, VTE prophylaxis in pregnancy and the puerperium. health.qld.gov.au PDF.
Calculator updated: September 13, 2026
Frequently asked questions
What does this VTE score show?
A point total that reflects venous thromboembolism risk in pregnancy or postpartum. It groups results into low, moderate, or higher risk bands.
Which items add points?
Age older than 35, higher BMI, selected pre-existing, obstetric, and transient factors. Each item lists its points in the Advanced section.
Can I leave height and weight blank?
Yes. The tool will use a typical pre-pregnancy BMI of 26 if no height and weight are entered.
Is this a diagnosis?
No. It supports counselling. A clinician should interpret the score with your history and local protocols.
What symptoms need urgent care?
Sudden shortness of breath, chest pain, coughing blood, a swollen or painful leg, or fainting need urgent assessment.
Support if you have experienced a loss
Reading about miscarriage, stillbirth, or infant loss can be difficult. If you have experienced a loss, you do not have to use this calculator or read the statistics. You may find it more helpful to talk with your care team or a support organization.
In the United States, groups such as:
offer information and bereavement support. If you are elsewhere, your local health service or a pregnancy and baby loss charity may be able to guide you to support in your region.